Abstract
Tennis requires the integration of physiological, technical, and cognitive abilities during intermittent high-intensity exercise; however, it remains unclear whether tennis-specific exercise induces different acute responses from duration-matched high-intensity interval training (HIIT). This randomized crossover study compared the acute effects of a tennis-specific exercise protocol (TSEP) and duration-matched HIIT on salivary biomarkers, working memory-related cognitive performance, and tennis-specific performance in 12 amateur competitive male tennis players (22.1 ± 1.6 years). Participants completed both protocols separated by a 7-day washout period. Salivary alpha-amylase (sAA) and secretory immunoglobulin A (sIgA) were assessed before, immediately after, and 30 min after exercise, whereas salivary creatine kinase (CK) was assessed before and 24 h after exercise. Tennis-specific accuracy, auditory 2-back target detection accuracy, and separated and combined dual-task performance were evaluated before and immediately after each protocol. Dual-task costs (DTCs) were also calculated separately for the motor and cognitive components. Both protocols produced significant time-dependent changes in sAA and sIgA (both p < 0.001), without significant condition or Condition × Time interaction effects. Salivary CK increased following both protocols, with a significantly greater Pre-to-Post-24 h increase following HIIT (Condition × Time, p = 0.032). The binomial generalized linear mixed-effects models showed significant overall time effects for single-task forehand and backhand accuracy and single-task 2-back target detection accuracy, whereas the time effect for serve accuracy was not statistically significant. However, none of the single-task performance outcomes showed a significant Condition × Time interaction. Among the separated dual-task outcomes, significant overall time effects were observed for backhand and cognitive accuracy, whereas forehand and serve accuracy showed no significant time effects. Combined dual-task accuracy also showed a significant overall time effect. None of the separated or combined dual-task outcomes showed a significant Condition × Time interaction. Relative motor and cognitive DTC outcomes were summarized descriptively and treated as exploratory because of non-normality, denominator instability, and one undefined value. Overall, both exercise protocols were followed by changes in selected salivary biomarkers and declines in selected technical and cognitive performance outcomes, but the analyses provided insufficient evidence that the magnitude of technical, cognitive, or dual-task performance change differed between TSEP and HIIT. In contrast, HIIT elicited a greater delayed salivary CK response. A multidimensional assessment combining physiological, biochemical, technical, cognitive, perceptual, and external-load measures may therefore provide a more comprehensive approach to monitoring acute fatigue in tennis.